Observation of NH X3Σ- as a Primary Product of Methylamine Photodissociation: Evidence of Roaming-Mediated Intersystem Crossing?

3+1 Resonance-enhanced multiphoton ionization and photofragment excitation spectroscopy have been used to identify NH X-3 Sigma(-) as a primary product of methylamine photodissociation after state-specific excitation to the S-1 state. On the basis of standard thermochemical data, NH X-3 Sigma(-) can be formed only in conjunction with closed-shell CH4 coproducts, indicating that dissociation must occur on the T-1 surface. It is proposed that the mechanism for the formation of triplet NH and CH4 involves intramolecular abstraction between frustrated radical products and is an example of roaming-mediated intersystem crossing.